Articles and health studies about drugs, addiction and alcoholism, including the most recent scientific and medical findings.

Wednesday, December 16, 2009

Q & A with Nora Volkow

NIDA director discusses cannabis, addiction vaccines, and gambling.

Recently, Addiction Inbox was offered the opportunity to submit questions to Nora Volkow, the director of the National Institute on Drug Abuse (NIDA). Dr. Volkow was kind enough to provide detailed answers by email. In her responses, she reveals a broad clinical understanding of addiction, and speculates on what this brain disorder might mean for “other diseases of addiction” like gambling.

Q: Clinical studies, like those by Barbara Mason at Scripps Institute, have documented a marijuana withdrawal syndrome among a minority of users. Are we prepared to say that marijuana is addictive? Why didn't we identify this syndrome years ago?

Nora Volkow: Absolutely, there is no doubt that some users can become addicted to marijuana. In fact, well over half of the close to 7 million Americans classified with dependence or abuse of an illicit drug are dependent on or abuse marijuana. It is important to clarify that while withdrawal is one of the criteria used to diagnose an addiction (which also includes compulsive use in spite of known adverse consequences), it is possible for an individual to suffer withdrawal symptoms without he or she being addicted to an abused substance.

Now, to answer your specific question, the reason for the relatively late realization that people who abuse marijuana can develop a cannabis withdrawal syndrome (CWS) if they try to quit is probably the result of at least two factors. First is the fact (which you hint at already) that a clinically relevant cannabis withdrawal syndrome may only be expected in a subgroup of cannabis-dependent patients. This may be partially explained by marijuana’s uptake into and slow release from fat cells, which can occur over days or weeks after last use. Thus, cessation of marijuana use may not be so abrupt, and could thereby diminish signs of withdrawal. The second factor relates to the small to negligible associations between recalled and prospectively assessed withdrawal symptoms, which may have precluded many previous, recall-based studies from detecting or properly characterizing CWS. It is also worth pointing out that other addictions (e.g., cocaine) were also not initially thought of as capable of triggering withdrawal symptoms.”

Q: Are there any anti-craving medications you are particularly excited about at this time?

Volkow: In the context of nicotine addiction, we have a host of nicotine replacement options as well as 2 medications that work through different mechanisms—all of which reduce craving and the risk of relapse during a cessation attempt, particularly when combined with some form of behavioral therapy. However, sustained abstinence from nicotine has been difficult to achieve, even with the current therapeutics that are available. So, at this point, I am very excited about a novel approach to the treatment of addiction—an approach that relies on vaccine development. Currently there are anti-nicotine vaccines in clinical testing, which are designed to capture the nicotine molecules while still in the bloodstream, thus blocking their entry in to the brain and inhibiting their behavioral effects. And while these vaccines were not intended specifically to reduce cravings, they appear to be effective in helping subjects who develop a high antibody response sustain abstinence over long periods of time. Even those people with a less robust antibody response to the vaccine, decreased their tobacco use. So this approach appears very promising.

Similarly, in the context of opiate addiction, we are very excited about the cumulative positive results of the clinical experience so far with buprenorphine, a long-acting partial agonist that acts on the same receptors as heroin and morphine, relieving drug cravings without producing the same intense "high" or dangerous side effects.

Q: You have suggested in the past that certain forms of overeating are addictions. There is good evidence for this. What about non-substance addictions, like gambling?

Volkow: The brain is composed of a finite number of circuits, for, for example, rewarding desirable experiences, remembering and learning about salient features and stimuli in the environment, developing emotional connections to other members of the social group, becoming aware of changes in interoceptive (internal) physiological states, etc. These and a few others are the circuits that the “world” acts upon. So it is almost by necessity that we’ll find significant overlaps in the circuits that mediate various forms of compulsive behaviors. We have yet to work out the details and the all important differences, but it stands to reason that there will be many manifestations of what we can call diseases of addiction. Thus, addiction to sex, gambling, alcohol, illicit drugs, shopping, video games, etc. all result from some degree of dysfunction in the ability of the brain to properly process what is salient, accurately predict and value reward, and inhibit emotional reactivity or deleterious behavior.

As we learn more about the significant overlaps at the genetic, neural, circuit, and systems levels we may be able to reap the benefits from complementary research into these various chemical and behavioral addictions.

15 comments:

Rob -A
said...

Yet again, reading this piece, I'm struck by this use of the term 'abuse'. perhaps the Dr could explain what she means by abuse, and why its only used for cannabis and not for nicotine or eating. I never abused drugs, I used drugs. Even as an addict, I only ever used. Crack abuse suggests theres a sensible level of use but no one will tell me the cut off point. The terms 'abuse' and 'misuse' are abused and misused by professionals and do nothing more tha=n elevate them above the people they argue they are helping. If anyone had ever told me I was a substance abuser, I would have told them where to go. I was a junkie but never an abuser.

The semantics of drug use is a tricky business. There are plenty of people who would highly resent being called a "junkie" but who could live with being called a drug "abuser." But I agree that "drug abuse" is not a very useful phrase.

Thanks for the post. Good Q&A.As a recovering and classified 'alcoholic' i certainly used pot before getting sober. Did I a 'abuse' it? It's a drug, like alcohol, that alters the brain. So, sure, I guess I did. I didn't get wasted each time I used it alone. I enjoyed it for the most part...but I don't do that any more...just like I don't drink.

I use it at times as a category--"drugs of abuse"-- to indicate psychoactive substances to which addiction-prone people can become addicted. Overall, "addictive drugs" is probably better jargon, although equally prone to misinterpretation, i.e.,if it's so addictive why ain't I addicted?

Let's not forget that the DSM IV (the manual used for diagnosing mental disorders) has been the source that mental health and medical professionals look to for guidance with regard to the abuse vs dependence criteria/lingo. My guess is that this is why the terms have taken root in the field. My interpretation of abuse is that it is a precursor to dependence. So...every person with an addiction disorder was initially an abuser and then the abuse became a dependency. Makes sense to me.

Abuse= 1 or more criteria within a 12-mo periodDependence= 3 or more criteria within a 12-mo period

Michelle--that line of thought makes good sense at the professional level, and thanks for pointing out the specific definititions. It's still unclear to me what the best informal term would be, in newspapers and popular discourse. They are all loaded terms in their way.

Maybe something like "substance tolerance" or "substance tolerance that has become obsessive and compulsive" would be better? Obsessive-compulsive substance use? Or, I really like the term "allergy" because it helps people understand better that there are some human beings that have a different biological response (a "more!" response) to substances than other people do.

Thanks for this great discussion! After working in this field for nearly 20 years,I am find myself even more confused by terms used by those who have problems in living due to the repetition of harmful behaviors. It is my considered opinion, we have not tackled the hard work of establishing agreed upon terminology between those in recovery and MD/PhD types that research addictive behaviors. For example, is there difference between the term "addiction" and the DSM IV-TR term "dependence?" Our semantics get in the way of effectively helping people change. Also, Stanton Peele in his book, "The Diseasing of America" makes a good arguement against the disease or allergy concept of addiction. Addictive behaviors, whether they be related to drugs or process addictions like gambling are far too complex to be lumped categorized or treated with a one size fits all approach.

I don't think the disease model is a case of "one size fits all." Different people require different kinds of treatment, the same as any other neurobiological disorder.

I agree that the semantics of addiction are a disaster--how does "dependence" differ from "abuse," for example?

Lastly, Peele's book makes as good a case as can be made that addiction has nothing in common with other diseases--and fails to convince. The latest version of the Peele argument (which requires one to discard some 25 years of excellent addiction science),is "Addiction: a Disease of Choice," I think it's called.

Michelle: "So...every person with an addiction disorder was initially an abuser and then the abuse became a dependency."

Thanks for posting that, Michelle. You are right that you need one or more criteria to be diagnosed with "abuse" and three or more to be diagnosed with "dependence." However, there are two separate lists of criteria which are of a different nature. One is not simply worse than the other.

Quoting your linked page, "According to the DSM-IV, a person can be abusing a substance or dependent on a substance but not both at the same time." A person can be dependent, showing tolerance, dependence, repeated attempts to quit, etc., but not meeting the criteria for abuse -- trouble with work, relationships, the law, endangering others, etc. DSM-IV lists nicotine dependence as a separate category but has no separate category for nicotine abuse. This is because nicotine (tobacco) is addictive, but doesn't cause the sorts of social problems associated with abuse.